Ag doped urchin-like α-MnO2 toward efficient and bifunctional electrocatalysts for Li-O2 batteries
Li-O2 batteries, Ag doped urchin-like MnO2, electronic structure, cycling stability
Rechargeable Li-O2 batteries (LOBs) have been receiving intensive attention because of their ultra-high theoretical energy density close to the gasoline. Herein, Ag modified urchin-like α-MnO2 (Ag-MnO2) material with hierarchical porous structure is obtained by a facile one-step hydrothermal method. Ag-MnO2 possesses thick nanowires and presents hierarchical porous structure of mesopores and macropores. The unique structure can expose more active sites, and provide continuous pathways for O2 and discharge products as well. The doping of Ag leads to the change of electronic distribution in α-MnO2 (i.e., more oxygen vacancies), which play important roles in improving their intrinsic catalytic activity and conductivity. As a result, LOBs with Ag-MnO2 catalysts exhibit lower overpotential, higher discharge specific capacity and much better cycle stability compared to pure α-MnO2. LOBs with Ag-MnO2 catalysts exhibit a superior discharge specific capacity of 13,131 mA·h·g−1 at a current density of 200 mA·g−1, a good cycle stability of 500 cycles at the capacity of 500 mA·h·g−1. When current density is increased to 400 mA·g−1, LOBs still retain a long lifespan of 170 cycles at a limited capacity of 1,000 mA·h·g−1.
Tsinghua University Press
Linna Dai,Qing Sun,Lina Chen,Huanhuan Guo,Xiangkun Nie,Jun Cheng,Jianguang Guo,Jianwei Li,Jun Lou,Lijie Ci, Ag doped urchin-like α-MnO2 toward efficient and bifunctional electrocatalysts for Li-O2 batteries. NanoRes.2020, 13(9): 2356–2364